National technical standards exist to define the physical and electrical characteristics of electrical plugs and their associated receptacles. The intent of these technical standards is to promote safety and operability between power sources and electronic devices that require electrical power. Historically, a particular electronic device would be designed for a specific source voltage and maximum current source and so would be manufactured with a fixed plug that is configured to insert into its complementary power-source receptacle. For example, an electronic device in North America requiring 220 volts and drawing a maximum current of 20 amperes would be supplied with a plug meeting the National Electrical Manufacturers Association (NEMA) 6-20 standard configured for insertion into a receptacle also conforming to the NEMA 6-20 standard. However, the NEMA 6-20 plug cannot be inserted into a receptacle capable of providing a lower 110 volt source voltage, such as a NEMA 5-15 standard receptacle.
However, electronic devices are currently being manufactured that have built-in power electronics capable of converting various input voltages into an appropriate electrical power for the device. While an electronic device might be configured with a NEMA 6-20 plug, it may be also operable with power provided by a NEMA 5-15 receptacle, even though not physically able to be inserted into the NEMA 5-15 without a plug adapter of some sort.
Regrettably, not every electronic device has built-in power electronics that are capable of accommodating various source voltages. A user that purchases an off-the-shelf electrical plug adapter to make use of a receptacle defined by a first technical standard for their electronic device having a plug defined by a second technical standard runs the risk of inadvertently tripping circuit breakers on the power source or destroying their electronic device because of an incompatible source voltage. Therefore, an adapter that can allow an electronic device to be used with various plug/receptacle combinations while protecting power sources and electronic devices from incompatible adapter and electronic device combinations is desired.
The subject matter discussed in the background section should not be assumed to be prior art merely as a result of its mention in the background section. Similarly, a problem mentioned in the background section or associated with the subject matter of the background section should not be assumed to have been previously recognized in the prior art. The subject matter in the background section merely represents different approaches, which in and of themselves may also be inventions.